Re: [kvm-unit-tests] x86: access: Add test for 5 level paging mode

["Radim Krčmář" <rkrcmar@redhat.com>]

2017-09-12 14:16+0200, Paolo Bonzini:
> On 25/08/2017 13:57, Yu Zhang wrote:
> > Provide paging mode switching logic to run access test in 5
> > level paging mode if LA57 is detected. Qemu parameter +la57
> > should be used to expose this feature, for example:
> > ./x86-run ./x86/access.flat -cpu qemu64,+la57
> > 
> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> > ---
> >  x86/access.c   | 17 +++++++++++++++--
> >  x86/cstart64.S | 43 ++++++++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 57 insertions(+), 3 deletions(-)
> 
> I need this for the test to pass in QEMU.  Probably the TLB is helping
> you on real hardware!  Pushed with this change.

  ...

> > diff --git a/x86/access.c b/x86/access.c
> > @@ -107,6 +108,8 @@ enum {
> >  #define AC_CPU_CR4_SMEP_MASK  (1 << AC_CPU_CR4_SMEP_BIT)
> >  #define AC_CPU_CR4_PKE_MASK   (1 << AC_CPU_CR4_PKE_BIT)
> >  
> > +extern void setup_5level_page_table();

GCC doesn't like that this declaration got dropped:

x86/access.c: In function ‘main’:
x86/access.c:1009:9: error: implicit declaration of function ‘setup_5level_page_table’ [-Werror=implicit-function-declaration]
         setup_5level_page_table();
         ^~~~~~~~~~~~~~~~~~~~~~~

We can also include instead:

diff --git a/x86/access.c b/x86/access.c
index 8268b0065467..a0c19dc701b7 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -3,6 +3,7 @@
 #include "desc.h"
 #include "processor.h"
 #include "asm/page.h"
+#include "x86/vm.h"
 
 #define smp_id() 0